Instrument test probes



9 1953 F. M. BENDER 2,846,658

INSTRUMENT TEST PROBES Filed June 6, 1955 FREOEk/GK M. BEA/DER 6 INVENTOR BY WX United States Patent Mal INSTRUMENT TEST PROBES Frederick M. Bender, Union N. J., assignor, by mesne assignments, to Daystrom, Incorporated, Murray Hill, N t J., a corporation of New Jersey Application June 6, 1955, Serial No. 513,543 1 Claim. (Cl. 339-108) This invention relates to electrical connectors and more particularly to dual purpose connectors which combine the characteristics of a clamp connector and an electrical probe.

Clamp connectors of the so-called alligator type are quite satisfactory when the conductive elements of the apparatus or network under investigation are well separated so that there is no possibility that the relatively wide jaws of such connectors will establish a short circuit between conductors of diflerent voltage and/ or polarity, but an elongated probe type of connector must be employed when the equipment under investigation is, for example, a radio or television unit having closely arranged conductors.

An object of this invention is the provision of electrical connectors of a clamp type and auxiliary devices which may be relatively rigidly supported by the clamp connectors to serve as probes.

More specifically, an object of this invention is the provision of a clamp connector having opposed linear jaws which are spring pressed toward each other, and an auxiliary probe with a grooved rectangular head which may be tightly gripped between the jaws of the clamp connector.

These and other objects and the advantages of the invention will be apparent from the following specification when taken with the accompanying drawing illustrating an embodiment of the invention. It is to be understood that the drawing is for the purpose of illustration and is not to be construed as defining the scope or the limits of the invention, reference being had for the latter purpose to the appended claim.

In the drawings wherein like reference numerals denote like parts:

Figure 1 is an exploded view of a test cable having connectors embodying the invention, and a fragmentary elevation, in part section, of an instrument with which the cable may be employed;

Figure 2 is an end elevation of the instrument;

Figure 3 is a fragmentary elevation, with part in section, of the connector end of the test cable;

Figure 4 is a perspective view of one of the probes; and

Figure 5 is a fragmentary sectional view, on an enlarged scale, on line 5-5 of Figure 3 in the direction of the arrows.

In the drawing, the reference character 1 identifies a multirange volt-ammeter which may be of the construction described in the co-pending application, Serial No. 513,490, filed June 6, 1955, by Francis X. Lamb, and which includes a pair of pin terminals 2 to which the plug end 3 of a test cable 4 comprising two wires 5 may be connected. A clamp connector 6 is secured to the outer end of each wire 5 by a screw 7; the connectors 6 being of conventional battery-type comprising two plates with their edges 6a flanged for greater strength, the inner ends of the plates being connected by the screw 7 and their outer ends being crossed and terminating in approximately parallel sections 6b having inturned mating jaws 60, with desirably serrated or toothed adjacent edges. The jaws are pressed into engagement by a stifi spring 8. Funnel shaped sleeves 9 of flexible insulating material, such as rubber, are preferably provided to enclose substantially the entire connectors except their jaw ends 60.

In checking the voltages on conductors of a radio or television unit, it is convenient to clamp one of the connectors 6 on the grounded chassis of the unit, but there is a possibility that the relatively wide jaw ends 6c of the other connector will inadvertently bridge across conductors which are at different voltages. This possibility is eliminated through the use of elongated probes in the form of pointed preferably cylindrical rods 9a having desirably relatively short integral heads 10 of non-circular and preferably square cross-section which may be mounted in one or both of the clamp connectors 6. Each probe has a peripheral groove 11 cut in its head 10 adjacent its junction with the rod 9a, to a depth such as to leave two head sections, the one toward the pointed end being a flange square in outline like the cross-section of the head, connected by a portion desirably corresponding in cross-section with said rod, to receive the jaws 6c of a clamp connector. The depth of the groove is so related to the thickness of the head 10 that the sections 612 of the clamp connection are substantially parallel to the respective sides of the noncircular probe head 10 when the jaws 6c are seated in the groove 11, see Figure 5. The dimensions of the probe head 10 are proportioned so that when the probe is clamped between the jaws of the connector, the probe head fits nicely Within the jaws, with the part of the probe between the outer head portion and the flange held against lateral movement between a pair of adjacent teeth of the connector plates. Consequently, the probe is securely held against turning, twisting or other movement which would be objectionable in actual use of the device and the probe normally will not become separated from the clip as the probe is Withdrawn from a device wherein the probe is firmly grasped, as in an outlet, socket, etc.

From the above description it is apparent that the pointed probes facilitate making electrical measurements at selected points in an electrical network such as a radio or television unit and which probes also lend themselves for ready insertion into a conventional outlet for checking line voltage. The insulated sleeves covering the body of each spring connector reduce the possibility of developing a short circuit during use of the device and protect the user against electrical shock.

Having now described my invention in detail in accordance with the requirements of the patent statutes what I desire to protect by Letters Patent of the United States is set forth in the following claim.

I claim:

A probe comprising a cylindrical rod pointed at one end and provided with a head integral therewith at its other end, said head being generally square in crosssection and longer than its transverse dimensions to provide two pairs of opposed flat faces, either pair of which is adapted to be engaged flatly for substantially its entire length by flat jaw plates of a clamp connector, and a flange also integral with said rod, generally square Patented Aug. 5,1958

inoufline and spaced fromthejadjacent endofsaid' head to receive between it and said head, inturned toothed mating edges of said clamp connector plates, whereby said cylindrical rod will be held against lateral movement between a pair of adjacent teeth of said mating edges, and also serving as a stop against which the outer surfaces of said toothed mating edges may engage.

References Cited in the file of this patent UNITED STATES PATENTS Frankel Apr. 3, 1917 Sachs Dec. 6, 1927 Olson Mar. 17, 1942 Novello Aug. 2, 1949 

